Where can I find a motorcycle visor that fits my helmet?!?!?

I have a DOT FMVSS 218 helmet. The model number is EXL-603 and it is a Medium. I am looking for a tinted visor that fits this helmet. I bought one off of ebay and it wasn't the right kind :(. If you can give me the website that would be great. I would like to pay under 20 dollars for this if possible. Thanks!